The plays are odd. One is akin to a cheerleader being hoisted on top of a pyramid when teammates lift a player into the air to receive an inbounds ball. It’s called a line-out.

There are 15 players to a side and they play 35-minute halves. Everybody plays defense, everybody plays offense, everybody tackles and everybody can carry the ball. Anybody can kick the ball.

Play is continuous, even after a tackle, unless there’s a penalty. You can pass laterally and backward, but not forward.

“Oh, it’s totally weird,” said Cathedral Catholic backs coach Karen Fong, a former UC Davis club player and member of the U-23 national team. “(But) once you start getting it, you’re like ‘Oh, that’s an amazing sport.’ ”

A few years ago, a group of rugby enthusiasts got together with the idea of starting a high school boys league. They hoped over time it would grow and that rugby could become a California Interscholastic Federation sport.

Rugby is not sanctioned by the CIF, but insiders are cautiously optimistic. The Southern California High School Rugby League has grown from six teams in the inaugural 2009-10 season to 21 teams — 11 in San Diego — this season. There are four divisions — two in San Diego and two in the Los Angeles/Orange County area.

“Most of the top high schools in San Diego are now embracing the rugby program,” said Ramon Samaniego, an assistant coach at Torrey Pines who is director of coaching for the San Diego Mustangs Youth Rugby Club. “It’s growing by leaps and bounds. It’s phenomenal.”

In order to grow the sport, the rules permit a student who attends a school that doesn’t have a team to join another school’s team in the same district.

Cathedral Catholic coach Glenn Irvine said the formation of the league was with the purpose of eventually becoming CIF certified. The league is following CIF guidelines and instituted a minimum 2.0 GPA requirement this year.

“That’s the whole intent,” said Irvine. “We’re trying to align ourselves as close as possible to what we know to be the CIF rules.”

The season goes from early December to late January with the postseason trickling into February. It culminated with a championship on Super Bowl Sunday when Belmont Shore Wilson beat host Cathedral Catholic 31-26.

Now that the high school season has concluded, the private club season begins and includes teams such as the San Diego Young Aztecs and the Carmel Valley-based Mustangs.

The Mustangs will host a tournament this weekend at Cathedral Catholic to benefit former Dons and Mustangs player Derek Thomas.

Thomas survived a horrific auto accident a year and a half ago that claimed the lives of four people. He was burned over 85 percent of his body and spent nearly a year at the Grossman Burn Center in San Fernando Valley after being given a 1 percent chance to live.

Thomas, 20, made his first rugby game appearance since the accident Friday night when his alma mater routed St. Augustine 57-14 in the semifinals.

Irvine, who coached Thomas on the inaugural Cathedral team, asked the former standout to hand out the jerseys to the starting players. Derek stayed to watch the game with his mom, Paula Thomas.

He told the players to leave everything on the field.

Dons juniors Alec Barton, Drew Gaffney and Joey Kuperman were freshmen when Thomas was a senior. They also played together on the Mustangs.

“Derek is my hero,” Barton said. “It’s awesome to see him come back from what happened. It inspired us to play with all our hearts. It was really something special to see him come out here.”

As he watched the game, Thomas said he was “really impressed” with the Dons’ performance.

“As a team, they’re doing really well,” he said.

Thomas said it was fun to see a few of his former teammates.

“It’s really exciting for me,” he said.

It was exciting for the players as well.

Gaffney said the Dons were energized by his presence and were happy to be able “to show him we really did learn from him.”

Said Kuperman: “It was amazing, especially after what he’s gone through for a year. To see him back on the rugby pitch is just awesome.”